A majority of computational systems are digital computers. Typically, addition, subtraction, multiplication, division and many other calculations are performed by digital computers. Analog type processing has also recently become important as the result of neural networks and other global information processing. In digital processing, a calculation of absolute value can be realized by inverting a sign bit. However, in analog processing, an electrical value is evaluated and is to be inverted in polarity. There has not been a circuit preferable for absolute value calculation of analog type, as far as the inventors know.